Arrangement for connecting and disconnecting two pipe sections of a fluid transfer system

ABSTRACT

An arrangement for connecting and disconnecting two pipe sections in a fluid transfer system. Each section includes a butterfly valve with a disk pivotally mounted inside, rotating about a swivel axis between a closed position closing the cross-section of the fluid flow and an open position opening the cross-section of the fluid flow. The swivel axes extend perpendicular to the pipe axis and parallel to each other. The swivel axes of the disks are eccentric relative to the axes of the sections to reduce the space between the disks in their closed position, when the sections are connected. The invention is useful for transferring liquefied natural gas.

FIELD OF THE INVENTION

The invention relates to an arrangement for connection and disconnectionof two pipe sections of a fluid transfer system, each constituting theend element of a pipeline and being configured in the form of abutterfly valve provided with a disk mounted so as to pivot inside thepipe section around a pivot axis between a position closing the crosssection of the fluid flow and a position opening of the latter, and anexterior device for control of the pivoting, the pivot axes extendingperpendicular to the axis of the pipe and parallel to one another.

BACKGROUND OF THE INVENTION

Connection arrangements are already known and make it possible toconnect together respective pipelines for supplying and receiving afluid in one direction or the other, between two stations, one of whichcould be a fixed station and the other of which could be a mobilestation.

Also known in the known connection and disconnection arrangements is anemergency disconnection device making it possible, in an extremesituation of drift or accident, for example, in case of fire, todistance the mobile pipe section from the fixed pipe section in order toprevent damage to the structure or wrenching off of the pipes whileensuring containment of the fluid in the pipelines.

In the known arrangements, the pivot axes of the disks of the two pipesections are spaced apart from one another, in the axial direction ofthe pipe sections, when the pipe sections are connected, thus enablingexecution of their pivoting movement between open and closed positions.This has the disadvantage that when the disks occupy their closedposition they delimit between them a relatively large space that isfilled with fluid. In event of emergency disconnection, this quantity offluid is lost into to the environment.

Such an incident is very serious when the transferred fluids aredangerous to people and the environment, or involve a risk of fire. Thisis the case in particular for the transfer of liquefied natural gas(LNG) between, for example, a loading or unloading terminal and aliquefied gas tanker.

SUMMARY OF THE INVENTION

The present invention aims to propose a connection and disconnectionarrangement of the type defined above, but which no longer has the majordisadvantage just stated.

In order to attain this aim, in the connection and disconnectionarrangement according to the invention, the pivot axes of the disks arearranged off center, with respect to the axis of the pipe sections, toreduce the space between the disks in their closed position when thepipe sections are pipe connected.

According to one feature of the invention, the pivot axes are offsetpependicular to the axis of the pipe sections, symmetrically withrespect to this axis.

According to yet another feature of the invention, the spacing betweenthe two disks is approximately zero when they occupy their closedposition.

According to yet another feature of the invention, the aforementionedtwo disks butt against one another in their open position in order tocancel out kinematic play and therefore any vibrations or flutter of thedisks that may be induced by instabilities of the fluid flow.

According to yet another feature of the invention, the pivot axis of adisk is formed by a shaft fixed by mounting on the rear surface of thedisk.

According to yet another feature of the invention, the pivot axis of adisk is arranged outside of the cross section of the fluid flow of thepipe section in which the disk is pivotably mounted.

According to yet another feauture of the invention, a tab is attached atthe periphery of a disk, and the pivot axis is located at a free end ofthis tab.

According to yet another feature of the invention, a device witharticulated arms is associated with a disk in order to ensure itspivoting, the free end of one of the arms being articulated to the disk,while the free end of the other arm is articulated to the wall of thepipe section.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood, and other aims,characteristics, details and advantages of it will appear more clearlyin the following explanatory description with reference to the appendeddiagrammatic drawings, given only as an example, illustrating twoembodiments of the invention in which:

FIG. 1 is a view in axial section of a connection and disconnectionarrangement according to the invention, along line I—I of FIG. 2, thedisconnection device only being represented diagrammatically;

FIG. 2 is a view in section of the arrangement according to FIG. 1, inthe direction of line II—II of FIG. 1, and shows the arrangement in theclosed position of the disks;

FIG. 3 is a view similar to FIG. 2 and shows the disks in their openposition;

FIG. 4 is a view of the arrangement according to FIG. 2 after emergencydisconnection;

FIG. 5 is a view in axial section of another embodiment of anarrangement according to the invention and illustrates the disks intheir closed position;

FIG. 6 is a view similar to FIG. 5 and shows the disks in their openposition; and

FIG. 7 is a view in section along line VII—VII of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 to 4 show a first embodiment of an arrangement for connectionand disconnection of two end sections of pipelines which are to beconnected, of a system for transfer of fluid 1 such as liquefied naturalgas, between two stations. One of the stations could be a liquefied gastanker and the other a loading or unloading terminal.

The figures show only the connection and disconnection arrangement,which bears general reference 1 and includes the two pipe sections 2, 3respectively mounted at the ends of the pipelines of the two stationsmentioned above. Each section is produced in the form of a butterflyvalve, and has circular disk 5, 6 which is mounted inside the pipesection, for which the fluid flow cross section is consequentlycircular.

Each disk 5 and 6 is mounted so as to pivot inside of section 2, 3 withwhich it is associated, respectively around an axis X, X′ between aposition of closing the fluid flow cross section, shown in FIGS. 1 and2, and a position of opening this cross section, illustrated in FIG. 3.

Each pipe section or valve 2, 3 has a general cylindrical shape and isprovided, at its end adjacent to the other pipe section, with annularcollar 8 giving the pipe section a flat front surface 9. The peripheralsurface of the two collars is configured in such a way that, in thestate of connection of the two pipe sections 2 and 3, which are thenaxially aligned, they form an assembly with an exterior truncatedconical contour 10 that is intended for being engaged in a groove with acomplementary V shape of an emergency disconnection device, indicateddiagrammatically by a ring 12 in FIGS. 2 and 3. This emergencydisconnection device is known and described in the French Patent No. 2580 367. Given that it is not part of the invention, it will not bedescribed in more detail. It is sufficient to indicate, for the sake ofunderstanding the invention, that ring 12 is composed, for example, oftwo ring segments 13, 14 which, when the pipe sections are connected,ensure the immobilization of the two sections in their connectedposition as shown in FIG. 2, and which can be separated, in the mannerindicated in FIG. 4 by arrows, in the event of emergency disconnection,thus releasing collars 8 of the two pipe sections, making it possible toseparate them, as seen also in FIG. 4.

It should be noted that the two ring segments 13, 14 remain connected topipe section 3. For more details concerning the disconnection device,one should refer to French Patent No. 2 580 367. It should also be notedthat this emergency disconnection device is represented in FIG. 1 onlyby the two circular elements 15 and 16 for assembling the two ringsegments 13 and 14.

According to an essential characteristic of the invention, exteriorfront surface 18 of each disk 5, 6, in closed position, is aligned withflat peripheral surface 9 of collar 8 of its pipe section, so that thetwo surfaces 18 are in contact with one another when the two pipesections 2 and 3 are connected.

The ability of disks 5 and 6 to pivot from this closed position intotheir open position represented in FIG. 3 is ensured by appropriatearrangements of their pivot axes.

According to another important characteristic of the invention the twodisks butt against one another in the open position. This arrangementmakes it possible to arrest the kinematic play and prevent any vibrationor flutter of the disks that may be induced by instabilities in thefluid flow.

In order to produce the two features, axis X of disk 5 and axis X′ ofdisk 6 are offset from one another in the direction of axis Y—Y of thepipe sections, on the one hand, and are symmetrically off-center withrespect to this axis Y—Y, on the other hand. The differences are roughlythe same in both cases. The two disks are thus in contact with oneanother in their closed position, and can both pivot around their axesin a synchronous manner in order to reach the open position representedin FIG. 3 in which the two disks are oriented parallel to axis Y—Y ofthe pipe sections while still being in contact on a portion of theirsurface. Each disk has therefore executed a pivoting movement of aquarter of a turn.

The pivot axis of each disk is materialized by operating shaft 21 andshaft stub 22 which are axially aligned. Shaft 21 is rotationallyfixedly connected in securing tab 23 situated high near the periphery ofthe disk, projecting from the rear surface of it, and is rotatablymounted in exterior tubular end piece 24 of the pipe section. Freeexterior end 25 of this shaft is configured so that it can be put inrotation. Shaft end 22 is installed by one end at 27 in the body of thepipe section and its end 28 is received, in such a way as to rotatefreely, in tab 30 provided on the rear surface of the disk near itsperiphery, low down.

It should be noted that a section carries, on its flat front surface 9,annular gasket 32 which is arranged in an appropriate annular recess.This gasket can be metallic, plastic, or made of a composite material.

FIGS. 1 to 3 represent module 1 in a connected state from engagement ofcollars 8 by their truncated conical peripheral surface in the V-shapedgroove of ring 12 of the emergency disconnection device. FIG. 4 showsthe two pipe sections 2 and 3 after an emergency disconnection. It isobserved, as indicated above, that this disconnection occurs by openingof ring 12, that is to say by radial movement of the two ring segments13 and 14 outward.

FIGS. 5 to 7 show a second embodiment of connection and disconnectionmodule 1 according to the invention. In this embodiment, the pivot axesof disks 5 and 6 are situated outside of the fluid flow cross section ofsections 2 and 3. For this purpose, tab 34, which extends towards theexterior, is provided at the periphery of disks 5 and 6, on their rearsurface. Installed in the other, free end of this tab is rotating shaft36 whose axis constitutes the pivot axis of the disk.

Each disk is operated through two articulated arms, namely first arm 41,which is articulated at 42 on the rear surface of the disk, and secondarm 43, which is articulated at its free end at 44 to the body of thepipe section. The shafts are articulated to one another at 45. The axesof articulation of the arms of course extend parallel to the pivot axisof the disk. As shown by the figures, in order to allow folding of arms41 and 43 during pivoting of the disk in its open position, representedin FIG. 6, the pipe section is provided with lateral protuberance 47which makes it possible to receive the two arms then folded on oneanother.

For the operation of its disk, for opening and for closing 5 or 6, eachsection is provided with tubular end piece 49 for passage of theoperating shaft, whose exterior control end is represented at 50. Theshaft acts on arm 43 at the location of its articulation 44 on the rearface.

It should also be noted that in the closed position of the disk,articulated arms 41 and 43 are aligned, providing bracing whichfacilitates taking up the stresses on the disk and locking of the closedposition.

The second embodiment of the module according to the invention,represented in FIGS. 5 to 7, has the advantage that the cross section ofthe fluid flow of the pipe sections is completely free, which makespossible scraping of the pipelines using a plunger element movingthrough the pipelines, pushed by a gas or liquid, in order to empty outthe fluid carried in the mobile pipeline.

The two embodiments of the invention have the shared advantage that thespace between the two disks, in their closed position, is practicallyzero, so that during emergency disconnection, after closing of the disksas seen in FIG. 4, there is no fluid which could enter the environment.Consequently, the risk of contaminating the environment is excluded.Thus, the module according to the invention is particularly suitable fortransfer of any fluid which is harmful to the environment, such as, forexample, liquefied natural gas. Another advantage of the invention liesin the light weight of the module. Yet another advantage of theinvention lies in the fact that the disks, in their open position, aresupported and immobilized, which prevents any vibration or flutterpossibly induced by instabilities of the fluid flow. In the case of thefirst embodiment, the disks are flattened against one another in theiropen position, as seen in FIG. 3. In the second embodiment, the disksare flattened against a zone of abutment of the pipe sections.

Numerous modifications can of course be made to the embodimentsdescribed and represented. Thus, it would be possible, in the context ofthe second embodiment, to place the axes of articulation of the disks ina diametrically opposed manner.

1. An arrangement for connection and disconnection of two pipe sectionsof a fluid transfer system, each pipe section comprising an end elementof a pipeline and a butterfly valve employing a disk pivoting inside thepipe section, around a pivot axis, between a closed position closing thepipe section against fluid flow and an open position opening the pipesection to the fluid flow, the pivot axes of the butterfly valvesextending perpendicular to the axes of the respective pipelines andparallel to each other, the pivot axes being off center with respect tothe axes of the respective pipelines, thereby reducing space between thedisks in their closed position when the pipelines are connected to eachother.
 2. The arrangement according to claim 1, wherein the pivot axesare offset perpendicular to the axes of the pipelines, symmetricallywith respect to the axes.
 3. The arrangement according to claim 2,wherein the space between the disks is approximately zero when the disksare in the closed position.
 4. The arrangement according to claim 3,wherein the disks butt against one another in the open positionpreventing kinematic play and vibrations or flutter of the disks inducedby instabilities of the fluid flow.
 5. The arrangement according toclaim 2, including respective shafts defining the pivot axes of thedisks, the shafts being fixedly mounted on rear surfaces of the disks.6. The arrangement according to claim 1, wherein pivot axes of the diskslie outside the cross section of the fluid flow in the pipelines inwhich the disks are pivotably mounted.
 7. The arrangement according toclaim 6, including respective tabs attached at peripheries of the disks,wherein the pivot axes are located in free ends of the tabs.
 8. Thearrangement according to claim 6, including a device with articulatedarms associated with the disks, a free end of a first of the arms beingarticulated to one of the disks, and a free end of a second of the armbeing articulated at a wall of the pipeline.
 9. The arrangementaccording to claim 7, wherein the pipelines have lateral protuberancesfor housing the articulated arms in the open position.
 10. Thearrangement according to claim 8, wherein the articulated arms are in abraced position when the disks are in the closed position.